Position repeating device and system



June 1943- T. M. FERRILL, JR., EIAL 2,442,754

POSITION REPEATING DEVICE AND SYSTEM l mv TOR THOMAS M. FERRILL JR. BY 1x2 5. ARRISON ATTCSRNEY Patented June 8, 1948 2,442,764 POSITION REPEATING DEVICE AND SYSTEM Y Thomas M. Ferrill, In, Hempctead, and Arthur E. Harrison, Bookville Centre, N. Y., aeslgnora to The Sperry Corporation, a corporation of Delaware Application November 20, 1943, Serial No. 511,010

8Claims. 1

Our invention relates to position repeating apparatus, generally, and more specifically is concerned with repeating devices including electrically controlled, heat-responsive expanslble and contractable operating elements, and their use in position repeating systems.

One of the objects of our invention is to provide a repeating device of the type comprising electrically controlled, heat-responsive expansible and contractable operating elements, applicable for use with either a direct current or alternating current self-synchronous positional transmitter, and to provide a system in which the receiver or repeater is free from ambiguity and which requires no transformation of motion between the transmitter and receiver.

Another object of our invention is'to provide a system in which the position-repeating device is' not subject to conditions of unstable equilibrium.

Still another object of our invention is to provide a repeater of the character comprising electrically controlled, preferably autogenous heating and heat-responsive, expansible and contractable members which is simple in construction and economically producible.

A further object of our invention is to provide a position repeating system in which a conventional self-synchronous transmitter is used with a voltagecontrolled, thermally operated positional repeater, the latter receiving a biasing voltage from the source of electrical energy employed in exciting the transmitter.

Yet another object of our invention is to provide a position repeating system in which a direct current positional transmitter is used with an electrically biased positional repeater of the voltage-controlled, thermally operated type. said bias being supplied to the repeater through a Y connected series of resistors.

Other objects and advantages of our invention will-become apparent as the description proceeds.

In carrying out our invention, we preferably employ a transmitter of the self-synchronous alternating current or direct current type, or of any suitable type providing a plurality of signal voltages in the output thereof and a repeater having voltage-controlled, indicator-positioning elements which, per se, are operated only in accordance with the magnitude the signal voltages such, ior example, as a thermal-responsive element responsive to heat which is controlled by the signal voltages.- In other words, the repeater of the present invention when excited only by Mel voltages derived from the transmitter 2 does not provide a phase-sensitive operation, that is to say, it is not affected by the polarity or phase sense of the signal voltages and therefore would be capable of providing a ambiguity or to provide readings 180 removed from each other for a single position of the transmitter. Furthermore, in accordance with our present invention, we apply a biasing voltage to the system and across each leg of the polycircuit connections between the transmitter and receiver or repeater whereby to eliminate the 180 ambiguity possibility which otherwise exists.

A more comprehensive understanding of our invention will be afforded from the following detailed description when considered with the accompanying drawing wherein like reference numerals have been used throughout to designate like parts, and in which Fig. 1 is a schematic diagram of an alternating current position repeating system embodying our invention;

Fig, 2 is a diagram of a system similar to that of Fig. 1, but adaptable for use with direct currents; and

Figs. 3, 4 and 5 are schematic diagrams of the system shown in Fig. 1 which illustrate the eiiect of applying bias voltage to the repeater for different positions of the transmitter rotor.

In the form of our invention illustrated in Fig. 1, an alternating current transmitter I l, of the conventional self-synchronous type is connected to a repeater l2, preferably of the character described in a copending application for an Electroexpansive device by Arthur E. Harrison and Edwin T. Jaynes, Serial No. 508,766, filed November 2, 1943.

Here, as in all position repeating systems, it is desired to have the angular position assumed by rotor I: of transmitter ll repeated by the indicating pointer ll of repeater II. In the device illustrated, this is accomplished by applying power to the heat-responsive, expansible and contractable members l5, l8 and I1, which are preferably autogenous heating and heat-responsive members, through the lines l8, l8 and 2|, respectively, the line 20 serving a purpose hereinafter to be described. The members II, It and I l are herein shown for exemplary purposes as linear elements having a fairly high resistivity and temperature coemcient of expansion whereby the signal voltages which are applied across the respective elements cause these elements to self-generate heat which in turn controls i717, length of these elements such that any changes in length thereof is proportional to a change in This power, v

pand or contract in accordance with the amount of power individually received. Under the expansion and contraction oi these members, rod 21, which is loaded against the normal attitude oi. these expansive members by spring 28, is caused to describe a simulated cone of motion about the pivot 29 as the rotor 23 of transmitter II is rotated. This motion is reduced to simple rotation by a disc 3| in which a slot 32 is provided for receiving a pin 33 carried on the end of rod 21. Through the free movement of pin 33 in slot 32, disc 3I is caused to rotate in accordance with the movement of rod 21. A shaft 34 on which the pointer I4 is carried is connected to disc 3| by a spider 35, and, by the application of our invention, now to be described, the pointer I4 is caused to repeat the position of rotor I3 oi transmitter II.

Considering now a position of the rotor I3 corresponding with that shown in Fig. 3, where the coupling of the rotor to secondary leg 24 is maximum, while that to legs 25 and 26 is /2 maximum, it is evident that with no bias connection between the neutral junctions 36 and 31, maximum current would be caused to flow through leg I5 oi the receiver, while a current of one-half this value would flow through each of the other receiver legs, I6 and I1. Thus, the expansion of leg I5 would be maximum, and the junction 31 would move in the direction, as shown in dotted lines in Fig. 3, to the position indicated as pin 33, Now, if the transmitter rotor is turned through an angle of 180, the above described conditions will again prevail. Thus, the thermal receiver system without bias is encumbered by a 180 ambiguity. It'follows, then, that with the direct application of the power output of transmitter II to repeater I2, the pointer of the latter may occupy one of two positions 180 from each other for one position of the rotor I3.

To remove this ambiguity of registration is the concern of the instant invention and the same is accomplished by applying a biasing voltage to repeater I2 through the conductor 20.

Thus, and with reference to Figs. 3, 4 and 5, which show the transmitter II and repeater I2 in slightly different form, it is seen that conductor connects source 22 to supply a biasing voltage between the neutral or junction points 36 and 31.

In Fig. 3 rotor winding 23 is schematically shown as linking stator winding 25 at an angle of 60; in Fig. 4, at an angle of and in Fig, 5, at an angle of 0, the rotor being rotated counterclockwise in successive 30 steps, as seen in the figures. If, for purposes of illustration, it be assumed that the output of source 22 is 100 volts, that the rotor winding 23 and each of the stator windings 24, 25 and 26 are of 300 turns, and that the resistance of each of the elements I5, I6 and I1 is 10,000 ohms, and further assuming that these resistances remain substantially constant,

the following circuit analysis may be made.

The total current flowing in conductor 20, due to the applied bias or 100 volts will be 30 milli- 4 amperes and in each of the elements I5, I6 and I1, 10 milliamperes. Further, since rotor winding 23 is at maximum coupling with stator winding. 24 and the phase of current induced therein is assumed additive to the bias current In this element, the total current-through winding 24 and electro-expansive element I5 is l1s=10+ 10 cos 0=20 milliamperes and the currents through elements I8 and I1, respectively, are

I I1s=In=10-10 cos 60=10-5=5 milliamperes similarly, when the rotor winding 23 is rotated to the position shown in Fig. 4, the currents flow-- ing in the expansive elements are:

I15=10+10 cos 30" =10+8.66=18.66 milliamperes Ii6=10+1o cos 9o=1o+o=1o.oo milliamperes and I17=10-10 cos 30=10-8.66=1.34 mllliamperes For the rotor position indicated in Fig. 5 the currents are:

I15=I1e=l0+10 cos 60=10+5=15 milliamperes in: 10-10 cos 0=l010=0 milliamperes In each of the above expressions for current, the first component of the sum is the current due to the biasing voltage and the second is that due to the voltage induced in the stator windings. In Figs. 3, 4 and 5, the phase of induced current flow is indicated by solid arrows and that oi the biasing current by dotted line arrows.

Continuing then, it will be clear that for the transmitter position shown in Fig. 3, the pin 33 of repeater I2, which is coincident with point 31, will be moved downwardly to the dotted line position shown. This follows since a current of 20 milliamperes is flowing in member I5 and a current of 5 milliamperes is flowing in each 01' the members I6 and I1. Inasmuch as the expansion of each of these elements increases as the current through it increases, element I5 will be elongated more than I6 and I1, which are elongated an equal amount, and the movement of the junction 31 will be as described. For the same reason,

the pin 33 will move to approximately the dotted line positions shown in Figs. 4 and 5, ior

and points intermediate to these will be passed through as rotor I3 is rotated continuously in a counterclockwise direction.

Now it will be seen that if the analysis of repeater currents for the respective rotor positions of Figs. 3, 4 and 5 is made for the corresponding three respective rotor positions with respect to each of the other two stator windings, 2d and 26, the point 33 will describe a substantially circular path of motion about its cold-element position as a center, and thus will move the pointer I4 of repeater I2 one revolution for each revolution of the transmitter rotor and in synchronism therewith. It will be seen further that point 33 can occupy only one position for each corresponding position of the transmitter rotor.

By the application of a biasing voltage in the manner just described, it is seen that a voltage controlled, thermally operated repeater may be used to repeat the position of any conventional self-synchronous transmitter without ambiguity, and without requirement of a motion transformation device between the transmitter and repeater.

Further, the position repeating system herein described possesses an advantage over other known systems in that a biased voltage controlled. thermally operated repeater is not sublect to a condition of "unstable equilibrium." By the quoted expression, it is intended to define that condition developed in a self-synchronous system when the power is off and the transmitter rotor isturned 180' out of position with the repeater. As is well knowmunder these conditions the repeater retains its position when the power is turned on and holds this position until the repeater rotor is extraneously moved or until its own vibrations destroy the unstable balanced condition and it turns through 180.

By closing a switch l0, Fig. 1, to the proper terminals to connect the repeating device I! in the circuit, a positional repeating system is provided in which a modification of the repeating device i2 is used. This modification comprises the card pointer arrangement for producing an indication of the position assumed by the pin 33, as embodied in Fig. 7 of the co-pending application referred to above. In'this particular embodiment no translating mechanism is used to convert the movement of rod 21 into simple rotation. Accordingly, the pin 33 is therefore free to move and is not subject to a dead-center position, regardless of the position taken by rotor 13 of transmitter ll.

Moreover, by the application of bias to the expansive elements l5, l6 and I1, as explained above, the repeater I2 is not subject to a 180 ambiguity. That this is true is readily apparent by inspection of any one of the Figs. 3, 4 or 5. For example, if the rotor of transmitter ll be turned through 180 from the position shown in Fig. 3, and with source 22 turned off, then when the current is turned on, under comparable static conditions, the direction of the induced currents will be reversed, the bias currents will remain unchanged, and point 33 will assume a position diametrically opposite to that shown.

The features of our invention relating to the use of electro-expansive repeaters in a direct current position repeating system, will best be understood in connection with Fig. 2. In Fig. 2, a standard type direct current position transmitter ll is connected to the electro-expansive position repeater i2. described above. Transmitter ll comprises a three segment circular resistor which is made up-of uniform winding sections 42, 43 and 44. Cooperating with this resistor is a double contact rotor having arms 45 and 35' which applies a direct current potential to the winding thereof between points 180. apart. Arms 43 and 33' which carry current from source 43 are mounted to rotate as a unit about the center of the three-winding resistor and are provided with contact points or brushes 41 and 31' for engagement with the resistor windings. Taps 43, 33 and ll deliver the output of transmitter 4| to the lines 32, 33 and 54 for transmission to the expansive elements II, It and "of repeater i2. A biasing voltage is supplied to the elements last referred to from source 53 through the Y connected equal resistances 56, 51 and 58.

Disregarding the biasing voltage from source 33 and the means for applying it, it is evident that repeater l2, whose elements l3, l3 and II are not sensitive to direction of current flow, will have a single reading for two positions of transmitter ll which results in an indication ambiguity of 180. Thus, if we consider the point of transmitter 4| to be the arm I5, and if we turn it to a position in which contact point 31' is. opposite tap 3|, it is seen that positive current will pass via conductor 33 through element H and negative currents via conductors 32 and 33 through elements II and I3. Moreover, assuming the transmitter ,windings to be uniform and equal, and the resistance of the expansive elements to be likewise, the current in element ll will be twice that in either element It or it and the pin 33 will move, as shown in dotted lines in Fig. 2, to the position indicated as pin 33.

Now, if the arms 43 and 35' be rotated through currents of the same respective magnitudes as in the above description will be passing through the elements l3, l8 and H, the only change being that the current directions will be reversed. Accordingly, pin 33 will occupy the same position as it did before and the registration of device I! will be ambiguous as to these two opposite positions of the transmitter rotor.

With the introduction of a biasing voltage into the system, however, this condition is overcome. Considering only that portion of the system which includes the repeater I2 and the means for applying a biasing voltage thereto, and making the necessary assumptions as to equal resistive paths, it will be evident that a positive bias voltage will produce equal positive currents flowing outwardly from the neutral point 31 in the elements l5, l3 and H as indicated by the dotted line arrows. The current in each element will be of the same magnitude and its direction, as stated above, will be fixed.

For the same transmitter positions considered above, the following conditions will obtain. When contact point 41' of transmitter 4| is at tap II. the transmitter will deliver a 'positive current over line 54 which opposes that due to the bias through element l1 and which will be additive to the bias in elements It and I6. Hence, the elements l5 and It will be elongated equallybut by a greater amount than element l1 and point or pin 33 will move to the position 30. It will be noted that with the bias voltage applied to the elements of device II, the point or pin 33 assumes a position 180 from that which it would take for the same transmitter setting without the biasing voltage.

Now, if transmitter contact 41 be moved to tap 5| by a 180 rotation of the transmitter rotor, a current will flow in element H which is additive to the bias current therein, and currents will flow in elements It and I3 which will oppose the bias currents in elements it and I6; so that point or pin 33 will move to the position 6|, which is 180 from the previous position. This analysis may be continued for one complete revolution of transmitter arm 43 and 43' and pin 33 will be seen to describe one complete revolution about its cold rod position 31 as a center.

Here as in the alternating current system, the biasing voltage prevents the repeater from assuming a single position for two diametrically opposed settings of the transmitter and renders it free from ambiguous registry.

It will be understood that the elements of the stator of the repeater which actuate the rotor may comprise separate electrical resistance elements for heat-generating purposes and thermally-responsive, expansible and contractable elements mounted in heat-responsive relation thereto for actuating the rotor but preferably, these functions are performed by the same elements as hereinbefore indicated. In other words, the elements l3, l3 and ll of the repeater which comprise the stator elements thereof are preferably autogenous heating and heat-responsive 7 members or members which become heated in accordance with the magnitude of the voltage impressed thereacross and which, by virtue of the change of temperature, expand or contract to thereby position the rotor of the repeater.

Modifications of our invention are of course possible and may present themselves in view of the foregoing disclosure. The descriptions and representations herein made are to be considered therefore as being illustrative only and nowise in a restrictive sense and our invention both as to spirit and scope is to be limited only by the appended claims.

' Whatis claimed is:

l. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator coma plurality of voltage-responsive elements ar-.

ranged in positions corresponding to those of the elements of said transmitter, correspondingly arranged elements of the stators beingconnected together in polycircuit fashion whereby to position the rotor of said repeater in accordance with the resultant of the magnitudes of the signal voltages impressed thereon,. a source of electrical energy for exciting said transmitter rotor, and means for applying a bias voltage across each of the circuit legs of said system whereby to effect a positioning of the rotor of said repeater in accordance with the algebraic sum of the bias and signal voltages to prevent a. 180 ambiguity in the indications afl'orded by said repeater.

2'. A position repeating system of the character recited in claim 1 in which an alternating current source is connected to excite said transmitter rotor and an alternating bias voltage is applied across each leg of the system.

3. A position repeating system of the character recited in claim 1 in which a D. C. source of electrical energy is connected to excite the transmitter and a D. C. bias'voltage is applied across each leg of the system.

4. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator comprising a plurality of elements for supplying signal voltages dependent in magnitude upon the angular relation of said stator elements and rotor, said elements being arranged in relatively fixed angular relationship and connected together in v signal voltages, a source of electrical energy for exciting said transmitter rotor, and means for applying a bias voltage across each of the legs of said system whereby to eil'ect a positioning of said rotor in accordance with the algebraic sum of the bias and signal'voltages to prevent a ambiguity in the indications afforded by said repeater.

5. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator comprising a plurality'ot elements for supplying signal voltages dependent in magnitude upon the angular relation of said stator elements and rotor, said elements being arranged in relatively fixed angular relationship, a repeater including rotor and stator, the stator of said repeater comprising a plurality of voltage-controlled, autogenous heating and heat-responsive members adapted to expand and contract in accordance with the voltages impressed thereacross, said heat-responsive members being relatively angularly arranged.

in positions angularly corresponding to those of the elements of said transmitter, correspondingly arranged stator elements and members being connected together in polycircuit fashion and said repeater members being connected to said rotor whereby to position the rotor of said repeater in accordance with the resultant of the magnitudes of the signal voltages, and means for applying a bias voltage across each of the legs of said system whereby to effect a positioning of said rotor in accordance with the algebraic sum of the bias and signal voltages to prevent a 180 ambiguity in the indications afforded by said repeater.

6. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator comprising a plurality of field windings having their axes relatively arranged in fixed angular relationship, a winding on said rotor, a source of alternating exciting current connected with said rotor winding, a repeater having a rotor and stator, said repeater stator comprising a plurality ot voltagecontrolled, heat-responsive elements relatively arranged in fixed angular relationships corresponding to the relative angular arrangement of the field windings of said transmitter, and corresponding ones of said heat-responsive elements and stator windings being connected together in polycircuit relation, said heat-responsive elements being operable to expand and contract in accordance with the temperatures to which they are subjected and including means responsive to the voltages impressed thereacross for generating 4 heat, said heat-responsive elements being connected to operate the rotor of said repeater and to position said rotor in accordance with the resultant of the magnitudes of the voltages supplied to said repeater, said source of alternating current being also connected across each leg of said circuit whereby to provide a bias voltage for efiecting the positioning of said rotor in accordance with the algebraic sum of the bias and signal voltages to prevent a 180 ambiguity in the indication afforded by said repeater.

7. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator comprising an endless resistance element having a plurality of output taps connected thereto in relatively spaced relationship and said rotor comprising spaced element-engaging wipers and a source of voltage connected therebetween, a repeater comprising a rotor and a stator, the stator of said repeater including a plurality of voltagecontrolled, autogenous heat-responsive members adapted to expand and contract in accordance with the voltages impressed thereacross and con- 9 nected to operate said rotor, said members being arranged in fixed angular relationship to correspond in number and angular relationship with the zones oi said resistance element lying between said output taps thereon, the elements of said repeater being connected across correspondingly arranged zones of the resistance element of said transmitter in polycircuit fashion whereby the rotor 01 said repeater will be positioned in accordance with the resultant of the magnitudes of the voltages supplied from said transmitter, and a source or electrical energy connected across each or the legs of said system whereby to eflect a positioning of said rotor in accordance with the algebraic sum of the bias and signal voltages to prevent a 160 ambiguity in the indications aiiorded by said repeater.

8. A position repeating system comprising a signal voltage transmitter having an electrically cooperable rotor and stator, said stator comprising an endless resistance elementhaving a plurality or output taps connected thereto in relatively spaced relationship and said rotor comprising spaced element-engaging wipers and a source or D. C. voltage connected therebetween, a repester comprising a rotor and a stator, the stator 01 said repeater including a plurality of voltageoontrolled, autogenous heat-responsive members adapted to expand and contract in accordance with the voltages imprused thereacross and connected to operate said rotor, said members being arranged in fixed angular relationship to correspond in number and angular relationship with the zones of said resistance element lying between said output taps thereon, the elements of said repeater being connected across correspondingly arranged zones of the resistance element of said transmitter in polycircuit fashion whereby the rotor of said repeater will be positioned in accordance with the resultant of the magnitudes of the voltages supplied from said transmitter, and a source of D. C. voltage connected across each of the legs of said system whereby to effect a positioning or said rotor in accordance with the algebraic sum of the bias and signal voltages to prevent a ambiguity in the indications afforded by said repeater.

THOMAS M. FERRILL, JR.

ARTHUR E. HARRISON.

REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 1,166,034 Akemann Dec. 28, 1915 1,197,212 Karninski Sept. 5, 1916 1,554,980 Ellis Sept. 22, 1925 1,966,448 Hayes July 1'7, 1934 2,004,421 Bmulski June 11, 1935 

